Naina Catherine Kapur, portrayed by Preity Zinta, is an angry young girl facing numerous struggles. Following her father's tragic suicide when she needed him the most, her devoted mother, Jaya Bhaduri, is left to raise Naina and her siblings, Shiv and Gia, alone. The family's situation is dire; the restaurant Jennifer runs is on the verge of collapse, and Naina’s paternal grandmother, Lajjo, blames her mother for the suicide. Lajjo's rejection of Gia, whom Jennifer adopted, further complicates their lives, leading to daily conflicts within their home.
Amidst this turmoil, Naina finds some solace in her MBA classmate, Saif Ali Khan, who seems to have a soft spot for her. Everything changes when Aman Mathur, played by Shahrukh Khan, enters Naina's life. His arrival brings a refreshing wave of optimism, helping to uplift his new neighbors from their sorrow. Although Naina is initially put off by Aman's exuberant personality, over time, she begins to appreciate his presence and ultimately falls for him.
Meanwhile, Rohit has long harbored feelings for Naina. Encouraged by Aman to express himself, he invites her for lunch but is caught off guard when she shares her affection for Aman instead. This revelation prompts Rohit to step back and eventually visit his parents, leaving Naina in a whirlwind of her newfound feelings. In an unexpected twist, Aman reveals to Naina that he is married to someone named Priya, actually his doctor, to prevent her from confessing her love.
As the truth unfolds, it's revealed that Aman is terminally ill, living with a condition that weakens his heart. Understanding his time is limited, he transforms into a selfless individual, eager to spread joy and encourage others to seize the day, since, as he poignantly puts it, > "Tomorrow might never come." This noble spirit leads him to sacrifice his own feelings to ensure Naina finds happiness in her relationship with Rohit.
Eventually, after much emotional turmoil, Naina agrees to marry Rohit. Aman plays a crucial role in mending the tension within Naina's family by exposing that Gia is her half-sister, brought forth from their father's affair. With this revelation, Lajjo softens her stance and accepts Gia, leading to a sense of unity as the family prepares for the upcoming wedding.
As time passes, Aman's health continues to decline. During Naina and Rohit's engagement festivities, an unexpected surge of excitement endangers Aman's life. In a fateful encounter, Naina learns the truth behind Priya's identity and realizes Aman had lied about his marriage to shield her from the heartache of his condition and to keep her from feeling alone. Despite his insistence that she marry Rohit, Naina grasps the depth of Aman's love for her.
The wedding occurs, and on Aman's deathbed, he extracts a promise from Rohit to care for Naina in his absence, ensuring that they will meet again in the afterlife. In a bittersweet farewell, Aman quietly passes away with his newfound friend by his side, while Naina observes from a distance.
Twenty years later, an older Naina reminisces about Aman's selfless love with her daughter, Gia, sharing how he was her first true love. No matter the years that have passed, both Naina and Rohit hold a cherished memory of Aman—they build a life together, never forgetting the significant impact he had on their lives. The cycle of love continues, as their family now eagerly anticipates the future.
